Thioltransferase (glutaredoxin) from Chinese cabbage: Purification and properties

초록

Thioltransferase, also known as glutaredoxin, was purified from Chinese cabbage (Brassica campestris ssp. napus var. pekinensis) by a combination of ion-exchange chromatography and gel filtration. Its purity was confirmed by SDS-polyacrylamide gel electrophoresis and its molecular weight was estimated to be about 12,000 which is comparable with those of most known thioltransferases. The enzyme utilizes 2-hydroxyethyl disulfide, S-sulfocysteine, α-chymotrypsin, insulin, and trypsin as substrates in the presence of reduced glutathione. The enzyme has K<inf>m</inf> values of 0.03-0.97 mM for these substrates. It appeared to contain dehydroascorbate reductase activity. The pH optimum of the enzyme was 8.5, when 2-hydroxyethyl disulfide was used as a substrate. It was greatly activated by reduced glutathione. Its activity was not significantly lost when stored at high temperature, indicating its thermostable character. It may play an important role in thiol-disulfide exchange in plant cells.

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